Cleaning and renewing used paint



Patented Aug. 14, 1951 OFFICE CLEANING AND RENEWING USED PAINT BRUSHESLuigi Rotelli, Framingham, Mass., assignor to Selma M. Rotelli, Framinham, Mass.

No Drawing. Application September 16, 1947, Serial No. 774,419

This invention relates to paint brushes and more particularly tocleaning and renewing paint brushes and has for its object the provisionof an improved method of, and cleaning agent for, cleaning and renewingof used paintbrushes.

Another object is to provide a safe, effective and economicallypractical paint solvent and disintegrating agent for use in the cleaningand renewing of used paint brushes.

Still another object is to provide an effective paint brush cleaner andrenewer.

Other objects will be apparent as the invention is more fullyhereinafter disclosed.

In accordance with these objects, I have discovered that the watersoluble salts of amino polyacetic acids, in warm to hot aqueoussolutions, are safe, efiective and economically practical agents for usein the removal of dried paint residues in used paint brushes, when usedalone or in association or combination with wetting agents or soap anddetergent compounds or in association or combination with said wettingagents and soap and detergent combinations.

By the term amino polyacetic acid I mean to identify that group of aminopolycarboxylic acids of which the following are typical examples:

tricarboxylic acid By the term water soluble salts of these said acidsI'mean to identify the alkali metal, ammonia and substituted ammoniasalts of said acids, as these said salts are th salts which are moststable in warm to hot aqueous solution, especially in the presence ofother basic ions.

The action of these said salts in warm to hot aqueous solutions upon thedried paint residues in used paint brushes appears to be one that isprimarily solubilizing towards the resinous compounds of the dried paintand distintegrating and partly solubilizing as to the metallic oxidepigments present in the dried paint. The rapidity 4 Claims. .(Cl.134-28) of the action of these said salts upon the dried paint residuesin the used paint brushes is wide ly variable depending upon the amountand kind of dried paint present, the temperature ofthe aqueous solution,and the concentration of the said salts present in the solution, as wellas the presence or absence of wetting agents and of soap and detergentcompounds in the solution.

Generally, I have found that low concentrations of the said salts in thesolution are more eifective than high concentrations, the chemicalactivity of the salts apparently increasing with increase in dilution orwith the degree of ionization of said salts in the solution.

Generally, also, I have found that with any given concentration of saidsalts in the solution the presence of a wetting agent accelerates therate of reaction of the said salts with the dried paint products in thebrush.

Generally, also, I have found that the presence of soap compounds andother detergents in the solution facilitates and accelerates thedisintegration of the dried paint products by promoting the dispersionand suspension of the released metal oxide pigments in th solution, andemulsification of the oils present and their polymerized and oxidizedcompounds in the solution.

Finally, I have found that it is generally desirable to employ a hotsolution rather than a warm solution as the rate of paint solubilizingand disintegration increases with increase in temperature. The besttemperature to employ depends somewhat on the type of bristle in thepaint brush but I have found that as a general rule a solutiontemperature approximating 7 0-80 C. is safely utilizable with mostbrushes.

As specific examples of the present invention. but not as a limitationthereof, in the cleaning and renewing of used paint brushes containingdried paint residues consistin principally of oil paints used generallyin the painting of the outside surfaces of wooden or frame houses, Iprepare an aqueous solution of one of the above identified salts of thesaid amino polyacetic acids containing about two level tablespoons ofthe the dry salt per quart of water, or a concentration of about 5 gramsof the said salt per 100 c.c. of solution, heat the solution to aboutC., immerse and agitate the used brush therein for an extended timeinterval until the paint residues therein are removed from the brush andthe bristles feel soft and pliable, then rinse the brush thoroughly inclear water and'dry the brush.

The precise time interval of immersion and agitation of the brush in thesolution will vary widely, depending upon the amount of the dried paintpresent in the brush, as one skilled in the art will recognize. but withbrushes heavily impregnated with dried paint the time interval normallyis only from 10 to 30 minutes.

By the addition to the solution of only a few grams per quart ofsolution of a wetting agent, such 'as lauryl sulfonate or the sodiumsalts of sulfonated hexyl alcohol, the time of immersion and agitationof the brush in the solution is materially reduced sometimes as much as50%.

By the addition of small amounts of alkali metal soap compounds or ofother types of detergents to the solution of the order of a few gramsper quart of solution, with or without the presence of a wetting agentin the solution, the removal of the paint deposits from the brushis-aiso materially accelerated due, it is believed, to the betterdispersion and suspension of the metallic oxide pigments throughout thesolution and emulsification of the oils present and their polymerizedand oxidized products in the solution.

of the examples given of the amino polyacetic acid salts effective aspaint solubilizing and disintergrating agents in accordance with thepresent invention, the tetra sodium salt of ethylene diamine tetraaceticacid in a concentration approximating 1 /2 ounces of a 30% aqueoussolution of said salt per quart of hot solution at a temperature ofabout 75 C. has been found to be exceedingly effective alone or in thepresence of wetting and/or soap and detergent compounds, in the removalof most paint residues.

The alkali metal salt of trimethyl amino-a,- a,-a"-tricarboxylic acid inconcentrations apper quart of solution gives equally as good results.

The sodium salt of diethylene triamine pentaacetic acid in about thesame concentrations given for the sodium salt of ethylene diaminetetraacetic acid, also gives substantially the same results.

All of the alkali metal and other salts above identified appearefiective within reasonable and economically practical lengths of timeas soluproxiznating 2 level tablespoons of the dry salt I vpaint brusheswhich comprises immersing and agitating the brushes in a warm to hotdilute aqueous solution of a water soluble salt of an amino polyaceticacid for a time interval eifective to obtain a solutioning anddisintegration of the resinous dried paint present in the brush by saidwater soluble salt of said amino polyacetic acid and suspension of thepaint pigments in said solution, and then rinsing the brush in clearwater and drying the same.

2, The method of claim 1. wherein'said solution contains also a wettingagent.

3. The method of claim 1, wherein said solution contains also adetergent compound.

4. The method of claim 1, wherein said amino polyacetic acid consists ofethylene diamine tetraacetic acid.

LUIGI ROTELLI.

REFERENCES CITED The following references are ofrecord in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,280,162 Catlett Oct. 1, 19182,240,957 Munz May 6, 1941 2,396,938 Bersworth Mar. 19, 1946 2,407,645Bersworth Sept. 17, 1946 2,412,945 Bersworth Dec. 24, 1946 2,438,038Craver Mar. 16, 1948

1. THE METHOD OF CLEANING AND RENEWING USED PAINT BRUSHES WHICHCOMPRISES IMMERSING AND AGITATING THE BRUSHES IN A WARM TO HOT DILUTEAQUEOUS SOLUTION OF A WATER SOLUBLE SALT OF AN AMINO POLYACETIC ACID FORA TIME INTERVAL EFFECTIVE TO OBTAIN A SOLUTIONING AND DISINTEGRATION OFTHE RESINOUS DRIED PAINT PRESENT IN THE BRUSH BY SAID WATER SOLUBLE SALTOF SAID AMINO POLYACETIC ACID AND SUSPENSION OF THE PLANT PIGMENTS INSAID SOLUTION, AND THEN RINSING THE BRUSH IN CLEAR WATER AND DRYING THESAME.